2.7.7. Alkaline phosphatase activity assay
ALP activity, as an early osteogenic marker, is used on days 7 and 14 to evaluate the osteogenic differentiation. The samples were washed with PBS and were lysed by RIPA buffer to measure the total protein and ALP activity. Based on the ALP activity kit (Pars Azmoon, Iran), after addition of the reagent, the optical density of the samples was measured at 405 nm and normalized against the total protein (BCA kit, Thermo Scientific).